This study presents the modification of cassava root husk-derived biochar (CRHB) with ZnO nanoparticles (ZnO-NPs) for the simultaneous adsorption of As(iii), Cd(ii), Pb(ii) and Cr(vi).

Removal of oil spillage from the environment is a global concern. Various methods, including the use of fibers as sorbents, have been developed for oil spill control. Oil palm empty fruit bunch (OPEFB) fiber is a plant biomass that may be acetylated by acetic anhydride using N-bromosuccinimide (NBS) as a catalyst; here, the extent of acetylation may be calculated in terms of weight percent gain (WPG). The modified fiber was used to remove Tapis and Arabian crude oils. The optimum time, temperature, and catalyst concentration were 4 h, 120 °C, and 3 %, respectively, and these parameters could achieve an 11.49 % increase in WPG. The optimized parameters improved the adsorption capacity of OPEFB fibers for crude oil removal. The acetylated OPEFB fibers were characterized by using Fourier transform infrared spectroscopy and field emission scanning electron microscopy to observe the functional groups available and morphology. Kinetic and isotherm studies were conducted using different contact times and oil/water ratios. The rate of oil sorption onto the OPEFB fibers can be adequately described by the pseudo-second-order equation. Adsorption studies revealed that adsorption of crude oil on treated OPEFB fiber could be best described by the Langmuir isotherm model.

Oil sorbents for cleanup operation should be of high sorption capacity, biodegradable, readily available, and lowcost. This is important for protection of the water environment, especially for oil spillage. Corn silk is a low-cost sorbent. In this study corn silk was treated by acetylation process to improve the sorption capacity. The process involved acetylation by acetic anhydride using N-bromosuccinimide (NBS) as a catalyst. Reaction time of 1, 3, 6, and 9 h, temperature of 90-120 o C and percentage of catalyst of 1-3 % were used in the experiment. The results showed that the highest oil sorption was 11.45 % weight percent gain (WPG). This was achieved at 3 % catalyst concentration in acetic anhydride and temperature of 120 o C for 6 h. A weight percent gain of 11.45 % was achieved. The effect of contact time on oil sorption capacity for different crude oil (Tapis and Arabian crude oils) was investigated. In general the sorption capacity reduced after the fifth cycle of sorption/ desorption. The characteristics of raw and treated corn silk were examined using FT-IR and FE-SEM. The treated corn silk as an organic waste material was found to have higher sorption capacity than that of the commercial synthetic sorbents such as polypropylene. This agriculture waste may be used to replace those of non-biodegradable oil sorbents.

Oil spills generally cause worldwide concern due to their detrimental effects on the environment and the economy. An assortment of commercial systems has been developed to control these spills, including the use of agricultural wastes as sorbents. This work deals with raw and modified mangrove barks (Rhizophora apiculata), an industrial lignocellulosic waste, as a low cost adsorbent for oil-product-spill cleanup in the aquatic environment. Mangrove bark was modified using fatty acids (oleic acid and palmitic acid) to improve its adsorption capacity. The oil sorption capacity of the modified bark was studied and compared with that of the raw bark. Kinetic tests were conducted with a series of contact times. The influence of particle size, oil dosage, pH and temperature on oil sorption capacity was investigated. The results showed that oleic acid treated bark has a higher sorption capacity (2,860.00 ± 2.00 mg/g) than untreated bark for Tapis crude oil. A correlation between surface functional groups, morphology and surface area of the adsorbent was studied by Fourier transform infrared spectrum, field emission scanning electron microscopy images and Brunauer-Emmett-Teller analysis. Isotherm study was conducted using the Langmuir and Freundlich isotherm models. The result showed that adsorption of crude oil on treated mangrove bark could be best described by the Langmuir model.